Switching of bacillus Calmette-Guérin (BCG) strain at second BCG therapy may reduce BCG-related side effects in patients with BCG-relapsing tumor

To investigate the clinical efficacy and safety of switching of BCG strain at the second BCG therapy in patients with BCG-relapsing non-muscle-invasive bladder tumor, defined as recurrence after achieving a disease-free status for 6 months.

METHODS

We retrospectively reviewed the clinicopathological characteristics of 97 patients treated with a second BCG therapy for BCG-relapsing tumor. At the initial BCG therapy, Tokyo-172 strain and Connaught strain were given in 71 (73.2%) and 26 (26.8%) patients, respectively. At the second BCG therapy, Tokyo-172 strain and Connaught strain were given in 56 (78.9%) and 15 (21.1%) patients who were initially treated with Tokyo-172 strain, and in 13 (50.0%) and 13 (50.0%) patients who were initially treated with Connaught strain, respectively. In other words, 28 (28.9%) patients were given a different BCG strain from a BCG strain given during initial BCG therapy (switching group), and 69 (71.1%) patients were given the same BCG strain (non-switching group). We examined whether switching of the BCG strain at the second BCG therapy affected the oncologic outcomes and incidence of BCG-related side effects.

RESULTS

The 5-year recurrence-free survival (RFS) rates in patients treated with Tokyo-172 to Tokyo-172 strain, Connaught to Connaught strain, Tokyo-172 to Connaught strain, and Connaught to Tokyo-172 strain were 52.9±7.7%, 63.5±14.8%, 85.7±9.4%, 41.0±14.7%, respectively (Figure). There was no significant difference in RFS between the switching and non-switching groups (64.7±9.6% vs. 54.8±6.9%, p=0.427). There was also no significant difference in the progression-free survival rate between the switching and non-switching groups (95.4±2.6% vs. 96.0±3.9%, p=0.674). In the non-switching group (n=51), 14% and 63% of patients experienced major BCG-related side effects during the initial and second BCG therapy, respectively. In the switching group (n=25), 44% and 32% patients experienced major BCG-related side effects during the initial and second BCG therapy, respectively. During the second BCG therapy, the rate of major BCG-related side effects was significantly higher in the non-switching group than in the switching group.

CONCLUSION

This study indicates that switching of the BCG strain at the second BCG therapy will reduce BCG-related side effects with equivalent clinical efficacy in patients with BCG-relapsing tumor.